Chemical characterization of cyanobacteria (Anabaena and Anabaena azollae) was examined by Curie-point pyrolysis-gas chromatography-mass spectrometry. 1) Pyrograms of each cyanobacteria showed a lot of peaks. 2) The multivariate statistical programs of cluster analysis correctly classified pyrograms as two groups (symbiosis and non-symbiosis) of cyanobacteria. 3) In the principal components analysis, the data to distinguish between symbiosis or non-symbiosis cyanobacteria are present in the first principal component. 4) The major peaks of the pyrolysis compounds from cyanobacteria were identified as phenol, 3-metyl-butanenitrile, 3-methyl-pyridene, 2,6-demethyl-pyridine, 2-ethyl-5-methylfuran, 2-furan-methanol, cyclohexylamine. The factor analysis suggests that these compounds achieve some important roles in the qualitative differences of cyanobacteria.

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Effect of application of sewage sludges and their ashes on soluble heavy metals in a soil was studied. Sludge samples consisted of two limed sludge cakes, two no-limed sludge cakes and four ashes prepared from theirslu dge cakes by 800℃ incineration treatment. These materials were applied to soil (volcanic ash soil) at a rate of 2.0 g P_2O_5 per 1.5 kg dry soil in pots. These were incubated in the dark at 30℃ for 1, 13, 26, 52 and 156 weeks. At the end of each incubation period, the soluble Fe, Mn, Zn, Cu, Pb and Cr were measured in the extracts by diethylenetriamine pentaacetic acid (DTPA) and 0.1 N HCl. The following results were obtained. 1) Amounts of soluble heavy metal were less by the application of ash than sludge cake (both limed materials and no-limed materials). Although these decreased ratios were different according to the species of metal and the method of extraction, the amount of soluble Zn and Cu were only a third or even less, regardless of the method of extraction. 2) Amounts of soluble heavy metal were decreased by application of sludge cakes gradually ; but these showed little or no change and were small after 156 weeks by application of ashes. 3) When extraction of HCl concentration increased, the amounts of extracted heavy metal were less by the application of ashes than application of sludge cakes. And amounts of extracted Zn and Cu were increased in proportion to eluate pH. These slopes of proportional straight-line were smaller by the application of ashes than application of sludge cakes even after 156 weeks. 4) Therefore, it is considered that insoluble forms of heavy metal by the incineration treatment were stable at least three years on upland conditions.

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Sucrose content was high in the extract of tubers extracted with 0.8 m^3 m^<-3> hot ethanol solution. Fructose and glucose content were about 10-20% of sucrose at harvest stages, which differed at another increasing stages of tubers. Hydroxyproline content was also high in the extract of tubers, which is known to be a sweet amino acid. The most effect was the difference of cultivars on the variation of sugars contents due to different conditions of cultivation. The next thing was the difference of soil types and the effect of regional condition was comparatively little. Hydroxyproline content was secondary division tuber>daughter tuber>mother tuber and the variation of contents was also much due to the difference of cultivars. In the effect of soil types, hydroxyproline content tends to be lower in the fields converted paddy of gley soils similar to sucrose contents and higher in the fields of well-drainaged paddy soils.

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The relationship between chemical components in taro (Colocasia esculenta) tuber and firmness of boiled tuber was examined. Chemical components that were related to the firmness of boiled tuber were contents of starch and potassium in the tuber and dry matter percentage on fresh tuber basis. Starch content and dry matter percentage of fresh tuber basis showed a positive correlation with the firmness of boiled tuber. On the other hand, content of potassium showed a negative correlation with the firmness. Non-starchy polysaccharides had no relation to the firmness except mother tuber of Ishikawa-wase. Swelling power, one of the properties of taro starch, had a relation to the firmness. However, amylose content and maximum viscosity had no relation to the firmness. It was concluded that both the amount of starch in the tuber and the swelling power of taro starch are directly related to the firmness.

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A simple direct determination of soil microbial biomass N is described. This method involves ninhydrinic estimation of nitrogenous compounds released by autolysis after incubating the soil with buffered (pH 7.0) toluene at 30℃ for 24 h, and it proved to be rapid, sensitive, and precise. Microbial biomass N of the non- and rhizosphere soils in rice paddy during the submerged period was determined by this method. Further, ATP content was determined by using the TCA-phosphate-paraquat method for comparison. The results are summarized as follows. 1) This method can be used to estimate the amount of microbial biomass N during the submerged period in paddy soil. For 9 microorganisms the mean value of K_N factor was 0.224. 2) Microbial biomass N calculating from ATP content (ATP-to-biomass C ratio of 138, and microbial biomass N-to-C ratio of 6) was nearly equal values to biomass N of the proposal method. 3) Microbial biomass N and ATP content of the non- and rhizosphere soils of rice were the largest in the manure plot, followed by the chemical fertilizer plot, and smallest in the no fertilizer plot. The different fertilizer managements had significant effect on the microbial biomass in the paddy soils. 4) Microbial biomass N and ATP content in the rhizosphere soil were much greater than those in the non-rhizosphere soil in each treatment, and the effect of the rhizosphere was clearly recognizable.

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We measured the factor of expression of nitrogenase activity by using slowgrowing soybean nodule bacteria in free-living state. The results were summarized as follows. 1) Expression of nitrogenase activity of slowgrowing soybean nodule bacteria does not need low aerobic culture condition that expressed nitrogenase activity under aerobic and anaerobic conditions. Expression of nitrogenase activity does need supplies of elements such as nitrogen source, carbon source and molybdenum, but does not need supplies of small elements and coenzymes. These elements functioned as follows : nitrogen source such as glutamine for cell growth ; carbon source for respiration substrate such as malic acid for supply of ATP and reducing power ; molybdenum for component of nitrogenase protein. 2) Carbon source for supply of ATP and reducing power were not sugar such as mannitol that is organic acid. These organic acids were succinic acid, malic acid, fumaric acid and citric acid that expressed nitrogenase activity by addition of these organic acids, but different activity was shown according to sorts and concentration of organic acid added. Maximum activity appeared with the addition of malic acid at 50 mM in these organic acids, and malic acid is effective carbon source for supply of ATP and reducing power of expression of nitrogenase activity in free-living state. 3) Influence of nitrogenase activity by inducement medium form showed nitrogenase activity on solid and liquid medium. Nitrogenase activity is larger on solid than liquid medium, amount of cell growth is larger on solid than liquid medium and amount of cell growth of liquid medium is about 50% of solid medium. 4) All 76 strains of soybean nodule bacteria showed nitrogenase activity. Expression of nitrogenase activity of these strains showed different activity by conditions of gas phase that could be categorized into 3 types : i.e., showing high activity under aerobic condition, showing high activity under anaerobic condition and both condition of aerobic and unaerobic. 5) From the results of these experiments, it was suggested that clear factor of expression of nitrogenase activity under addition of many factors can be elucidated by the use of simple composition such as GI medium.

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We have scrutinized a tube culture method for studying Frankia and its woody host-plant interactions. The results are summarized as follows. 1) When the crude Frankia cell suspension prepared from surface-sterilized root nodules of native Oobayashabushi (Alnus sieboldiana) plants was poured dropwise onto the host plants aseptically grown in the test tube containing the N-free H_<OAGLAND> culture medium, it was frequently observed to form effective nodules with high nitrogen fixing activity on root system of host plants. 2) When the root nodules formed in the test tube were surface-sterilized, fragmented and cultured in a proper culture medium for Frankia cells, multiplication of Frankia-like cell appeared. Subsequently, the successive cultures of these cells in the modified Qmod culture medium for Frankia was useful for purification of Frankia cells in the category of the cultural and morphological characteristics as well as its nitrogen fixing ability. 3) Inoculation of Frankia cells resulted in the nodule formation at high frequency (at almost 100%) on the Oobayashabushi plants aseptically grown in the test tube, and also on the Yamahannoki (Alnus hirsuta) plants (at 60%). The method used above clearly showed the salient features for isolation and purification of Frankia plants. Moreover, the method minimizes the problem of space requirement for studying specific plant-Frankia interactions.

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We analyzed the experimental results of calcium silicate application to rice plants. These experiments were practiced in the north-east (Tohoku), middle (Hokuriku), and south-west (Kyushu) of Japan in 1964-1986. 1) Nine out of 18 plots showed the increase of brown rice yields as a result of the application of calcium silicate. The average of the rate of increased yield in the effective plots was 5%. 2) The positive correlation was observed between the dry matter weight and N% , K% and also Mn%, of the rice seedlings which was used in the effective plots, but the relation between the weight and Mg%, similarly N% and Mg%, was negative. On the contrary, in the rice seedlings which were used in the ineffective plots, the positive correlation was found only between P% and K%, and we are not able to find a certain relation between the dry matter weight and the nutrients. From the above results, we supposed that the rice seedlings of the effective plots had a stronger nutrio-physiological activity compared with the seedlings of the ineffective plots. 3) The dry matter weight of rice plants at the time of the last bearing tiller emergence had the positive strong relation with the weight of seedlings. In the effective plots, moreover, they had the positive close connection with N% in the seedlings, the negative with Mg%. However, in the ineffective plots they only had the positive relation with P% and K% in the seedlings, but the significance of a coefficient of correlation was low. 4) From the above, we supposed the nutrio-physiological activity in the rice seedlings held an important position in regard to the effect of application of calcium silicate.

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